---
title: NSMigrationSourceObjectKey
framework: coredata
role: symbol
role_heading: Global Variable
path: coredata/nsmigrationsourceobjectkey
---

# NSMigrationSourceObjectKey

Key for the source object.

## Declaration

```swift
let NSMigrationSourceObjectKey: String
```

## Discussion

Discussion To access this key in a custom value expression string in the Xcode mapping model editor use $source.

## See Also

### Constants

- [NSMigrationManagerKey](coredata/nsmigrationmanagerkey.md)
- [NSMigrationDestinationObjectKey](coredata/nsmigrationdestinationobjectkey.md)
- [NSMigrationEntityMappingKey](coredata/nsmigrationentitymappingkey.md)
- [NSMigrationPropertyMappingKey](coredata/nsmigrationpropertymappingkey.md)
- [NSMigrationEntityPolicyKey](coredata/nsmigrationentitypolicykey.md)